How do I convince my mom that she deserves better?

I can’t stand my mom’s boyfriend (or exboyfriend)– I dont know anymore. everybody in my family doesn’t like him, my brothers and I HATE him, he has no friends, he has trouble with his work & family, etc. he’s been with my mom 3 years on and off. -more from an agruing point of view. whenever he is with my mom, he treats her like shyt. everything goes his way or he will biitch. if you get on his badside he will literally yell, swear, say the nastyest things to you. my mom won’t do ANYTHING about it. they have “broken up” so many times before, buht they always get back together. whenever he isn’t with my mom, he is always texting & calling her saying “I’m sorry, I love you, I dont want to lose you, etc” bullshyt like that after he just said “fuuck you, I don’t want you anymore”. then she’s like “I dont ever want to talk to you again” thennn like the next say she starts talking to him and denying it to my bro’s and I. he knows I don’t like him. my mom and him had went to couple therapy a while back ago and even the therapist said that he has a problem and no body can help him and that the relationship betwen him and my mom wasn’t a good thing. he is veryyy verbally abusive. I told my mom how I felt about him and she just doesn’t do shyt about it. she doesn’t care and I’m starting to believe that she doesn’t think she’ll find someone better out there… what should I do to convice her?